Problem with uart and ethernet communication

[Altera_Forum]

I have same problem with uart communication. 

I want receive data from ethernet and send to UART and vice versa.  UART to Ethernet is OK, but Ethernet to UART is not OK.  # define NETWORK_PORT 5000# define BUFFER_SIZE 32 # define true 1# define false 0  static char data_buffer[BUFFER_SIZE];  void DieWithError(const char *msg) {  perror(msg);  exit(1); }   int open_socket(void) {  int listen_fd;  int incoming_fd;  struct sockaddr_in my_addr;  struct sockaddr_in other_addr;  //socklen_t other_addr_len;  int other_addr_len;  int yes = 1;   // create socket.  listen_fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);  if(listen_fd == -1)  DieWithError("socket");    if(setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) {  DieWithError("setsockopt SO_REUSEADDR");  }  if(setsockopt(listen_fd, SOL_SOCKET, SO_KEEPALIVE, &yes, sizeof(int)) == -1) {  DieWithError("setsockopt SO_KEEPALIVE");  }          my_addr.sin_family = AF_INET;  my_addr.sin_port = htons(NETWORK_PORT);  my_addr.sin_addr.s_addr = INADDR_ANY;  memset(my_addr.sin_zero, '\0', sizeof(my_addr.sin_zero));  if(bind(listen_fd, (struct sockaddr *)&my_addr, sizeof(my_addr)) == -1)  DieWithError("bind socket");   printf("Listening on %s, port %d.\n", inet_ntoa(my_addr.sin_addr), ntohs(my_addr.sin_port));   // listen  if(listen(listen_fd, 1) == -1)  DieWithError("listen socket");   // accept connection.  other_addr_len = sizeof(struct sockaddr_in);  if((incoming_fd = accept(listen_fd, (struct sockaddr *)&other_addr, &other_addr_len)) == -1)  DieWithError("accept socket");    // close socket.  if(close(listen_fd) == -1)  DieWithError("close old socket");   printf("New connection from %s, port %d.\n", inet_ntoa(other_addr.sin_addr), ntohs(other_addr.sin_port));   return incoming_fd; }  // close socket void close_socket(int fd) {  if(close(fd) == -1)  DieWithError("close socket"); }  // open uart. int open_serialport(void) {  int fd;   // open uart.  fd = open("/dev/uart", O_RDWR | O_NOCTTY | O_SYNC);  if(fd == -1)  DieWithError("open serialport");      return fd; }  // close serialport void close_serialport(int fd) {  if(close(fd) == -1)  DieWithError("close serialport"); }  int fromuartTask(void) {     int network_fd;  int serial_fd;  fd_set read_fds;  struct timeval tv;  int tmp;    // open uart and network connection  serial_fd = open_serialport();  network_fd = open_socket();   while(1)  {    FD_ZERO(&read_fds);  FD_SET(network_fd, &read_fds);  FD_SET(serial_fd, &read_fds);    tv.tv_sec = 0;  tv.tv_usec = 0;   // wait.  if(network_fd > serial_fd)  tmp = network_fd;  else  tmp = serial_fd;   if(select(tmp + 1, &read_fds, NULL, NULL, &tv) == -1)  DieWithError("select");    // Ethernet data ??  if(FD_ISSET(network_fd, &read_fds))  {  // recv from ethernet.  printf("wait for network data.\n");  tmp = recv(network_fd, data_buffer, BUFFER_SIZE, 0);    if(tmp == -1)  DieWithError("recv");  if(tmp == 0)  break;   // write to uart.  if(write(serial_fd, data_buffer, tmp) == -1)  DieWithError("write");   printf("Got network data.\n");  }   // Data from UART??  if(FD_ISSET(serial_fd, &read_fds))  {  // read from uart.  printf("waiting for serial data.\n");  tmp = read(serial_fd, data_buffer, BUFFER_SIZE);    if(tmp == -1)  DieWithError("read");  // send to ethernet.  if(send(network_fd, data_buffer, tmp, 0) == -1)  DieWithError("send");   printf("Got serial data.\n");    }    }   // close socket and serial port  close_socket(network_fd);  close_serialport(serial_fd);   return 0; }

[Altera_Forum]

It was a long time age that I tried, but IIRC the select() call doesn't work well with the Interniche stack. It only detects incoming data on one of the sockets, but not both. 

This was a long time ago (with Quartus 7.2 I think) so it may have been fixed since then. Otherwise you could try to use two threads to read data on each socket.